From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v1 7/8] powerpc/32s: Use SPRN_SPRG_SCRATCH2 in DSI prolog
Date: Wed, 25 Nov 2020 07:10:52 +0000 (UTC) [thread overview]
Message-ID: <f9f8df2a2be93568768ef1ac793639f7914cf103.1606285014.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <da51f7ec632825a4ce43290a904aad61648408c0.1606285013.git.christophe.leroy@csgroup.eu>
Use SPRN_SPRG_SCRATCH2 as an alternative scratch register in
the early part of DSI prolog in order to avoid clobbering
SPRN_SPRG_SCRATCH0/1 used by other prologs.
The 603 doesn't like a jump from DataLoadTLBMiss to the 10 nops
that are now in the beginning of DSI exception as a result of
the feature section. To workaround this, add a jump as alternative.
It also avoids fetching 10 nops for nothing.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/include/asm/reg.h | 1 +
arch/powerpc/kernel/head_book3s_32.S | 24 ++++++++----------------
2 files changed, 9 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index a37ce826f6f6..acd334ee3936 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1203,6 +1203,7 @@
#ifdef CONFIG_PPC_BOOK3S_32
#define SPRN_SPRG_SCRATCH0 SPRN_SPRG0
#define SPRN_SPRG_SCRATCH1 SPRN_SPRG1
+#define SPRN_SPRG_SCRATCH2 SPRN_SPRG2
#define SPRN_SPRG_603_LRU SPRN_SPRG4
#endif
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 51eef7b82f9c..22d670263222 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -288,9 +288,9 @@ MachineCheck:
DO_KVM 0x300
DataAccess:
#ifdef CONFIG_VMAP_STACK
- mtspr SPRN_SPRG_SCRATCH0,r10
- mfspr r10, SPRN_SPRG_THREAD
BEGIN_MMU_FTR_SECTION
+ mtspr SPRN_SPRG_SCRATCH2,r10
+ mfspr r10, SPRN_SPRG_THREAD
stw r11, THR11(r10)
mfspr r10, SPRN_DSISR
mfcr r11
@@ -304,19 +304,11 @@ BEGIN_MMU_FTR_SECTION
.Lhash_page_dsi_cont:
mtcr r11
lwz r11, THR11(r10)
-END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
- mtspr SPRN_SPRG_SCRATCH1,r11
- mfspr r11, SPRN_DAR
- stw r11, DAR(r10)
- mfspr r11, SPRN_DSISR
- stw r11, DSISR(r10)
- mfspr r11, SPRN_SRR0
- stw r11, SRR0(r10)
- mfspr r11, SPRN_SRR1 /* check whether user or kernel */
- stw r11, SRR1(r10)
- mfcr r10
- andi. r11, r11, MSR_PR
-
+ mfspr r10, SPRN_SPRG_SCRATCH2
+MMU_FTR_SECTION_ELSE
+ b 1f
+ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
+1: EXCEPTION_PROLOG_0 handle_dar_dsisr=1
EXCEPTION_PROLOG_1
b handle_page_fault_tramp_1
#else /* CONFIG_VMAP_STACK */
@@ -760,7 +752,7 @@ fast_hash_page_return:
/* DSI */
mtcr r11
lwz r11, THR11(r10)
- mfspr r10, SPRN_SPRG_SCRATCH0
+ mfspr r10, SPRN_SPRG_SCRATCH2
RFI
1: /* ISI */
--
2.25.0
next prev parent reply other threads:[~2020-11-25 7:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-25 7:10 [PATCH v1 1/8] powerpc/32s: Always map kernel text and rodata with BATs Christophe Leroy
2020-11-25 7:10 ` [PATCH v1 2/8] powerpc/32s: Don't hash_preload() kernel text Christophe Leroy
2020-11-25 7:10 ` [PATCH v1 3/8] powerpc/32s: Fix an FTR_SECTION_ELSE Christophe Leroy
2020-11-25 7:10 ` [PATCH v1 4/8] powerpc/32s: Don't use SPRN_SPRG_PGDIR in hash_page Christophe Leroy
2020-11-25 7:10 ` [PATCH v1 5/8] powerpc/603: Use SPRN_SDR1 to store the pgdir phys address Christophe Leroy
2020-11-25 7:10 ` [PATCH v1 6/8] powerpc/32: Simplify EXCEPTION_PROLOG_1 macro Christophe Leroy
2020-11-25 7:10 ` Christophe Leroy [this message]
2020-11-25 7:10 ` [PATCH v1 8/8] powerpc/32: Use SPRN_SPRG_SCRATCH2 in exception prologs Christophe Leroy
2020-12-10 11:29 ` [PATCH v1 1/8] powerpc/32s: Always map kernel text and rodata with BATs Michael Ellerman
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